Closures molded from polymeric materials have met with widespread acceptance in the marketplace. Closures of this nature, which can be efficiently formed by compression molding or injection molding, are particularly suitable for use on bottles and like containers, including those having carbonated and non-carbonated contents.
Several important design criteria must be considered in connection with efficient and cost-effective use of these types of molded closures. Material savings is always desirable, since this facilitates cost-effective use of such closures. At the same time, the closures must be configured to exhibit the necessary strength and impact resistance, including the necessary resistance to deformation attendant to top-loading of the closures, such as during shipment and storage of stacked groups of containers.
In addition to meeting the necessary performance criteria, it is important that plastic closures be configured for efficient manufacture, such as attendant to formation by compression molding. During this formation process, internally threaded plastic closures are typically “stripped” from an associated male molding plunger, without any relative “unthreading” rotation. It is important that closures exhibit the requisite flexibility to permit removal from the associated molding apparatus in this fashion, while at the same time avoiding undesirable deformation of the molded closure.
Features of the present plastic closure provide enhanced, cost-effective performance, while facilitating high-speed manufacture.